Re: Look and Feel

[Nicolas Roard]

Le 14 févr. 05, à 13:29, Jesse Ross a écrit :

> > Camaelon will have extra overhead -- but it's just because it uses
> > pixmap instead of drawing things "by hand" using NSBezierPath et al.
> >
> > In other words, if you were to implements a new "native" look using
> > pixmaps it will be as slow as camaelon.
> >
> > ...
> >
> > As I said, the actual architecture is very close to that with the
> > GSDrawFunctions class. Camaelon extends that class and modify widgets
> > so they use it, and thoses modifications will hopefully rolled in
> > GNUstep in the future. So you'll have a clean separation of the way
> > widgets looks -- all the drawing will be in GSDrawFunctions.
>
> So, the interface is currently created using vector paths, if I'm 
> reading
> this correctly?

Yes. All the drawings on GNUstep are vectoriel. Don't forget that on 
NeXT there was DisplayPostScript ! GNUstep ditched DPS because the 
implementation we had was buggy and slow, but the model is the same -- 
that's why you don't have antialiasing using the xlib backend for 
example, while you have it for free in the art backend...

> How difficult would it be to create a new UI using vectors
> instead then?

It will be more difficult, because you will need to *code* it. Using 
pixmaps is much easier.

If/when we have a good and *fast* NSSVGImageRep (for example) or even a 
NSEPSImageRep or NSPDFImageRep, we could use SVG, EPS or PDF instead of 
images...

It's probably already doable (ViewPDF provides it afaik) but it's also 
probably very slow..

> Would that have to happen directly in the -gui code, or is
> there a way to make a theming engine that uses vectors instead?

er... like I said a few times, there's not really a difference with 
something that is in the -gui code, and something that is in a gui 
theme bundle...

Objective-C is a runtime-based language; as such the messages are sent 
and mapped at runtime. That's why you can poseAs: a class -- ie, say to 
the runtime, "here is my new shiny class A, make all the call to that 
other class B automatically redirected to my class A".

A gui "theme bundle" is a code loaded at runtime by gnustep; in general 
(well, the one that exists, Camaelon and WildMenu..) just categorize 
(== replace some methods of some classes) or poseAs (==replace some 
class) existing gui code.

Anything that's doable in gui is doable in a theme bundle..

>  That would
> be much faster, correct, since we're not relying on pixmaps?

actually, yes and no. Using NSBezierPath or other PS operators to 
create a new look is probably faster than compositing a lot of images. 
But it's more work, and on the other hand, images allow you to do some 
good caching, so the speed isn't too much impacted, and images let you 
create more detailed look. Using something a NSPDFImageRep or other 
"vectoriel" format would probably not be very interesting, because you 
would need to rasterize the PDF before displaying it. But well it could 
be fun to test.

--
Nicolas Roard
"Any sufficiently advanced technology is indistinguishable from magic."
 -Arthur C. Clarke